When designing switched power converters, and in particular high voltage DC/AC converters or inverters, thermal management is of utmost importance. Since a considerable amount of energy is dissipated in the components of the converter, with a resulting heat emission, thermal dissipation must be arranged for.
In prior art high voltage switching converters, a base plate is provided on which a plurality of elongated heat sinks are arranged parallel to each other. On both sides of each heat sink, power transistors are arranged for switching a high DC voltage. The power transistors are mounted to a printed circuit board (PCB) which is placed on top of the heat sinks with the transistors facing the base plate. Between each power transistor and its corresponding heat sink, a ceramic substrate is arranged for insulting purposes. Typically, grease is applied on both sides of the ceramic substrate to facilitate better thermal contact. Further, the power transistors must be assembled onto the board such that they are carefully fitted with the heat sink and the ceramic substrate; it is important that the transistors are in close contact with the heat sink and the intermediate substrate in order to attain a low thermal resistance and thus god thermal management. It is generally of great significance for switched power converters that heat is carried off from the power transistors.
However, in the above described prior art converter, it is difficult to assemble the transistors such that they on the one hand all press against their respective heat sink with sufficient force and on the other hand that wedging of the transistors between the heat sinks is facilitated without an installer having to apply excessive force when the board is placed on top of the heat sink.